How do orders get executed. Is it completely sequential By the time they were put in?

Does it make any difference if I do a market order?

Will that execute only after all the other orders I put in have executed or not?

Put it this way. I put in a limit order to sell a while ago, what would happen if I followed that up with a market order just to make sure. Would the market order execute only if the limit order failed?

The most likely execution order is the one which leaves you with the greatest possible loss. Unless you are the one orchestrating events. ^^

This also means that the most profitable action is to either use another exchange or wait until the spasms end and regroup at whatever level that is. The panic-sells always bounce at a much lower level than they stabilize at. (This deep bounce is induced by people who sell blindly during the fall, which is practically everyone except the orchestrator.)

From what I have seen... The lag will delay any order request... if you do a market, it won't hit until that order catches up with the lag time.

So if lag is 5 min, a market order will be placed in 5 minutes... Which due to lag you have no clue what is happening during those five minutes.

If you have a limit order in "open" state it will trigger at that price. If you goofed and try and cancel, that will take as long as the lag... aka five minutes in this example.. during which it could be filled.

Mtgox isn't smart about market and limit orders it will perform which ever order is placed first. So if your market order hits before the limit order, it will be filled and your limit may or may not also fill depending on the funds in your account.